Urban Road Safety

How to deal with complexity?

D. Fleury – INRETS

Conference Physics and the City.

Bologna 15-17 December 2005

Department of Accident Mechanisms (INRETS)

Research in the field of Road Safety A multidisciplinary team (cognitive psychology,

ergonomics, civil engineering, town planning, law, political science, vehicle engineering)

The “system” 'approach as a theoretical framework

Interdisciplinary modelling

In Depth Accident Investigation (IDAI)Études détaillées d’accidents (EDA)

Complexity in the traffic system

The result of situational heterogeneity and multiple retroactions

The most common modelling of the road traffic system: [man]-[vehicle]-[road environment]

Specific research issues based on system analysis

Micro-regulation of the traffic system

Man (driver-pedestrian) regulates the (M/V/R) system in real time

Macro-regulation and social management of safety

Regulation performed in “response” delay time, with the observation of user behaviour (driving speeds, accidents, perceived risks, opinions, etc.)

Accidents are the symptom of a dysfunctional situation in the interactions between components in the M/V/R system

Information input and processing

Action on control units

Man Vehicle

Road environment

Dynamic behavior of the vehicle

Simplified functional model for the analysis of safety (INRETS)

Informationinput

Processing Choice and decision-making

Action Conse-

quences

Example of a functional model (MDAI project)

Phased models

Baker and Fricke (1986)

Phase analysis and space analysis

General conditions

Driving situation

Accident situation

Emergency and collision situations

network and choice of itineraries

characteristics of the carriageway and section

break related to a section or particular location

(intersection, for example)

fine characteristics of the

location

Consistency (between the different levels) of the layout in question

Improve the overall consistency of the entire (socio-technical) traffic system to improve safety.

Parallel between individual user control and actions on space.

Accident analysis, not restricted to immediate interaction, leading to actions for treating black spots as well as town planning and transportation policy.

A field of research: the notion of typical scenarios as “road pathologies"

Example

Wide through road, problems of visibility (night, wetness, age, advertising, etc.)

Driving situation

High speed, low attention

Pedestrian preparing to cross outside a pedestrian crossing

Accident situation

View obstructed by a standing vehicle, the pedestrian crosses

Emergency situation

No manoeuvre (surprise)

Collision situation

Pedestrian hit

Example of research on accident scenarios : from IDAI (EDA) to intelligent safety diagnosis

1. Construction of “scenarios” on a panel of accidents

2. Scenarios recognition through police reports (and accident files)

Structure of the knowledge field

Symptoms (data) for recognition

Statistical inferences

3. Links between road environment and accident scenarios

Road types

Scenarios profiles (% of each scenario)

Modelling Micro-regulation

Systems with decision-making and memory centres (ref.: Boulding)

TASK AND ITS CONSTRAINTS

Ambience: road & traffic MAN

VEHICLE ACTIVITY

memorization

decision

Models coming from psychology and safety diagnosis of large socio-technical systems

On the role of memorisation.

Rasmussen model (1980), level of cognitive operation: problem, procedural and automation resolution.

On decision-making and motivation.

Risk models: risk homeostasis (Wilde, 1988), zero risk (Näätänen and Summala, 1974), threat avoidance (Fuller, 1984).

Macro-regulation and social management of safety

Environment: road & traffic

MAN

VEHICLE

TASK AND ITS CONSTRAINTS ACTIVITY

memorization

decision

TECHNICAL MANAGEMENT

To improve safety, we have to understand the Functional descriptions of the system and the regulation goals

Understanding how the system operates (functions)

Understanding the process of action

Analysing the implicit models on which this action is based

Research example:

Urban Travel Plan design (Plans de Déplacements Urbains)

Obligations in:

Law on the Air and Rational Energy Use – 1996

Law on Solidarity and Urban Renewal – 2000

Follow-up work meetings for nearly one and a half years

Design Process

1

Processus de conception

The “Relatiogram” – Frédérique Hernandez

2

Le « relatiogramme » - Frédérique Hernandez

The Urban Travel Plan as a scene for actors

Construction of a “reference project” by clustering "operational projects":

technical objects (tramway…) technical layout concepts (traffic calming…)

4

Marseille Urban Travel Plan (Hernandez, 2000)

Three main scenarios:

“town centre” scenario grouping together projects such as "pedestrian priority hypercentre", "tramway" and "cycling",

“periphery” scenario with secondary centres, 30 km areas, Southern Urban Boulevard, etc.

“cluster” scenario with the “regional express rail network” and the “Blancarde Aubagne route"

Referring to an "island strategy" concerning automobile traffic

6

Some conclusions:

Safety research entails modelling

Different levels of representations of unsafe situations

Both aspects: techniques and decision making

How to make explicit the models of action

Stressing the “unspokens” of planning (importance of Ring roads, forgetting mopeds and motocycles, etc.)

The possible consequences on safety (accident scenarios)